Nucleic Acids

Two types of nucleic acids:

1. Deoxyribonucleic acid (DNA)

2. Ribonucleic acid (RNA)

DNA carries genetic code (synthesis of polypeptides) and is self-replicating

RNA assists the functioning of DNA

Nucleotides: subunits of nucleic acids

Each nucleotide has:

• a pentose sugar (deoxyribose or ribose)
• a nitrogenous base (deoxyribonuleotides: adenine, guanine, cytosine and thymine / ribonucleotides: adenine, guanine, cytosine and uracil)
• a phosphate group (attached to pentose sugar)

• Nucleotides are joined by condensation reactions to form phosphodiester bonds (between phosphate of one nucleotide and the C3 of the pentose of the other nucleotide)
• The polynucleoide strand has a free 5-end (phosphate attached) and a free 3-end
• DNA has two anti-parallel strands
• Bases are joined by hydrogen bonds, improving stability (A and T, G and C (base pairing))
• Nucleotides join at slight angles, forming the double helix
• RNA molecules are single stranded and much shorter than double stranded DNA and RNA has no base pairing